Pole mismatch compensation via feedback control approach

Abstract

A system including an error signal generating module to generate an error signal based on (i) back electromotive force sensed from a motor and (ii) a predetermined speed of the motor. The error signal includes noise due to mismatched poles of the motor. A noise elimination module eliminates components of the noise having frequencies N times a frequency of rotation of the motor from the error signal and generates a corrected error signal, where N is an integer greater than or equal to zero. A control module generates a first control signal based on components of the corrected error signal, generates a second control signal based on components of the error signal, and rotates the motor at the predetermined speed based on (i) the first control signal and (ii) the second control signal. The components of the corrected error signal have higher frequencies than the components of the error signal.

1. A system comprising:
 an error signal generating module configured to generate an error signal based on (i) back electromotive force sensed from a motor and (ii) a predetermined speed of the motor, wherein the error signal includes noise due to mismatched poles of the motor; 
 a noise elimination module configured to
 eliminate components of the noise having frequencies N times a frequency of rotation of the motor from the error signal, and 
 generate a corrected error signal, where N is an integer greater than or equal to zero; and 
 
 a control module configured to
 generate a first control signal based on components of the corrected error signal, 
 generate a second control signal based on components of the error signal, and 
 rotate the motor at the predetermined speed based on (i) the first control signal and (ii) the second control signal, 
 
 wherein the components of the corrected error signal have higher frequencies than the components of the error signal. 
 
     
     
       2. The system of  claim 1 , wherein the noise elimination module is configured to:
 generate a correction signal based on the error signal, and 
 generate the corrected error signal by subtracting the correction signal from the error signal. 
 
     
     
       3. The system of  claim 2 , wherein the noise elimination module is configured to:
 generate a first scaled signal by scaling the error signal, 
 generate a delayed signal by delaying the correction signal, 
 generate a second scaled signal by scaling the delayed signal, and 
 generate the correction signal by summing the first scaled signal and the second scaled signal. 
 
     
     
       4. The system of  claim 1 , wherein the control module is configured to generate the first control signal by (i) filtering the components of the error signal and (ii) scaling the components of the corrected error signal. 
     
     
       5. The system of  claim 1 , wherein the control module is configured to generate the second control signal by (i) filtering the components of the corrected error signal and (ii) passing the components of the error signal including a direct current (DC) current component of the error signal. 
     
     
       6. The system of  claim 1 , wherein the control module is configured to generate the second control signal by (i) integrating the error signal and (ii) scaling the integrated error signal. 
     
     
       7. The system of  claim 1 , wherein the control module comprises:
 a high-pass filter configured to
 pass the components of the corrected error signal, and 
 generate the first control signal; and 
 
 a low-pass filter configured to
 pass the components of the error signal including a direct current (DC) component of the error signal, and 
 generate the second control signal. 
 
 
     
     
       8. The system of  claim 7 , wherein:
 the high-pass filter has a higher gain than the low-pass filter at frequencies of the components of the corrected error signal; and 
 the low-pass filter has a higher gain than the high-pass filter at frequencies of the components of the error signal. 
 
     
     
       9. A rotating storage device comprising:
 a controller that comprises the system of  claim 1 ; and 
 the motor, 
 wherein the motor is configured to rotate a storage medium of the rotating storage device at the predetermined speed. 
 
     
     
       10. A method comprising:
 generating an error signal based on (i) back electromotive force sensed from a motor and (ii) a predetermined speed of the motor, wherein the error signal includes noise due to mismatched poles of the motor; 
 generating a corrected error signal by eliminating components of the noise having frequencies N times a frequency of rotation of the motor from the error signal, where N is an integer greater than or equal to zero; 
 generating a first control signal based on components of the corrected error signal; 
 generating a second control signal based on components of the error signal, wherein the components of the corrected error signal have higher frequencies than the components of the error signal; and 
 rotating the motor at the predetermined speed based on (i) the first control signal and (ii) the second control signal. 
 
     
     
       11. The method of  claim 10  further comprising:
 generating a correction signal based on the error signal; and 
 generating the corrected error signal by subtracting the correction signal from the error signal. 
 
     
     
       12. The method of  claim 11  further comprising:
 generating a first scaled signal by scaling the error signal; 
 generating a delayed signal by delaying the correction signal; 
 generating a second scaled signal by scaling the delayed signal; and 
 generating the correction signal by summing the first scaled signal and the second scaled signal. 
 
     
     
       13. The method of  claim 10  further comprising generating the first control signal by (i) filtering the components of the error signal and (ii) scaling the components of the corrected error signal. 
     
     
       14. The method of  claim 10  further comprising generating the second control signal by (i) filtering the components of the corrected error signal and (ii) passing the components of the error signal including a direct current (DC) current component of the error signal. 
     
     
       15. The method of  claim 10  further comprising generating the second control signal by (i) integrating the error signal and (ii) scaling the integrated error signal. 
     
     
       16. The method of  claim 10  further comprising:
 generating the first control signal by passing the components of the corrected error signal using a high-pass filter; and 
 generating the second control signal by passing the components of the error signal including a direct current (DC) component of the error signal using a low-pass filter, 
 wherein the high-pass filter has a higher gain than the low-pass filter at frequencies of the components of the corrected error signal, and 
 wherein the low-pass filter has a higher gain than the high-pass filter at frequencies of the components of the error signal. 
 
     
     
       17. The method of  claim 10  further comprising:
 controlling a rotating storage device comprising the motor; and 
 rotating a storage medium of the rotating storage device at the predetermined speed using the motor.